DESCRIPTION: This is a proposal to identify the brain structures and pathways involved in conditioned learning. The investigator has identified the major neural components that support a conditioned limb flexion response in the cat and it appears to parallel in many respects that found for the conditioned nictitating membrane response in the rabbit, with a major difference being that the cat conditioned flexion response involves the somatosensory cortex and the rabbit nictitating membrane response does not. However, the red nucleus appears to be an important component in both. The animals will be trained in a classical and an operant conditioning task. Dr. Voneida will then transect the corticorubral tract in the first experiment. In the second experiment he will use the same tasks, but with microinjections of Lidocaine and known transmitter agonists and antagonists in the red nucleus. Dr. Voneida proposes that the red nucleus contains a critical motor trigger zone for conditioned limb flexion, and when it is deactivated it should prevent the expression of the conditioned response while leaving the pedal push response undisturbed.